Assesment of the Effect of Boundary Conditions on Cylindrical Shell Modal Responses

The modal analysis of circular cylindrical shells with general boundary conditions is rarely studied in the literature probably because of a lack of viable experimental verification. Moreover, the utilization of existing solution procedures, which are often only customized for a specific set of different boundary conditions, can easily be inundated by the variety of possible boundary conditions encountered in the real life practice. Present research focusing on an assessment of boundary condition effects in modal response estimation. For this study a circular cylindrical shells with outer diameter of OD300 employing arbitrary boundary conditions has been fabricated and physically tested. A set of four cylinders with fixed thickness of 0.5 mm has been rolled from the stainless steel AISI 304 grade and joined by plasma welding. The self-frequency measurements have been performed by means of laser scanning vibrometer (Polytech PSV400). Several boundary conditions have been studied during the experimental setup: free/free, simply supported/free and simply supported/simply supported in order to assess the robustness of modal responses. A numerical verification with FE code ANSYS has been performed in parallel in order to demonstrate the accuracy and convergence of the current solutions. The modal characteristics and vibration responses of elastically supported shells are summarized and the effect of various boundary conditions over stiffness configurations has been discussed.